Molecular basis of disturbed extracellular matrix homeostasis in stress cardiomyopathy

[Histopathological diagnostics of arthrofibrosis]

Joint surgery is one of the most important and successful disciplines in surgery; nevertheless, complications still occur, especially in total knee arthroplasty and surgery of the anterior cruciate ligament. A significant disease in this context is arthrofibrosis. This review article presents the cellular and molecular pathogenetic concept of arthrofibrosis, the spectrum of histopathological diagnostics and differential diagnostics and a classification into joint endoprosthesis-associated and non-joint endoprosthesis-associated arthrofibrosis is proposed. The basis of the histopathological diagnostics is the standardized tissue removal with subsequent fixation in formalin. In the case of joint implant failure and the problem of endoprosthesis-associated arthrofibrosis, the histopathological diagnostics can be carried out according to the consensus classification of synovia-like interface membrane (SLIM). Arthrofibrosis is characterized by fibrosis, a high fibroblast cellularity with immunohistochemical detection of cytoplasmic beta catenin expression. The presence of endoprosthesis-associated arthrofibrosis is probable above a threshold of 20 beta catenin positive fibroblasts per high-power field (HPF). The diagnosis of a non-endoprosthesis-associated arthrofibrosis can be classified according to the joint pathology algorithm. Diffuse non-endoprosthesis-associated arthrofibrosis is characterized by generalized proliferation of connective tissue in the whole joint and localized circumscribed arthrofibrosis is characterized by a nodose cyclops-like fibrosis. The clarification of the cause of arthrofibrosis is based on an interdisciplinary cooperation. In addition to the histopathological diagnostics, this includes clinical, surgical, biomechanical, arthroscopic, microbiological, laboratory parameter and radiological findings.

Molecular Mechanisms of Takotsubo Syndrome

Takotsubo syndrome (TTS) is a severe but reversible acute heart failure syndrome that occurs following high catecholaminergic stress. TTS patients are similar to those with acute coronary syndrome, with chest pain, dyspnoea and ST segment changes on electrocardiogram, but are characterised by apical akinesia of the left ventricle, with basal hyperkinesia in the absence of culprit coronary artery stenosis. The pathophysiology of TTS is not completely understood and there is a paucity of evidence to guide treatment. The mechanisms of TTS are thought to involve catecholaminergic myocardial stunning, microvascular dysfunction, increased inflammation and changes in cardiomyocyte metabolism. Here, we summarise the available literature to focus on the molecular basis for the pathophysiology of TTS to advance the understanding of the condition.

Klinische Diagnostik, Differenzialdiagnostik, Pathogenese- und Stadienmodell der Arthrofibrose

Die Arthrofibrose (AF) gehört zu den häufigsten Komplikationen nach Verletzungen und operativen Eingriffen an Gelenken, v. a. nach Gelenk- und Kreuzbandersatz. Alle großen Gelenke können betroffen sein, am häufigsten ist es jedoch das Kniegelenk. Es kommt zur schmerzhaften Bewegungseinschränkung durch Vermehrung von fibrotischem Gewebe innerhalb und teilweise auch außerhalb des Gelenks. Der normale Heilungsprozess ist durch mechanische und emotionale Stressoren sowie starke Schmerzreize gestört. Die AF tritt zu 90 % schon wenige Tage nach der Verletzung oder Operation auf, sodass die Qualitätsstandards nicht erreicht werden können. Durch Physiotherapie und Rehabilitation kann oft keine wesentliche Verbesserung der Funktion erreicht werden, sodass die Aktivitäten des täglichen Lebens (ADL) stark eingeschränkt sind. Klinische Diagnostik, Differenzialdiagnostik sowie ein neues Pathogenese- und Stadienmodell der primären AF mit den daraus abgeleiteten therapeutischen Prinzipien werden vorgestellt.

Pathophysiology of Takotsubo Syndrome - a joint scientific statement from the Heart Failure Association Takotsubo Syndrome Study Group and Myocardial Function Working Group of the European Society of Cardiology - Part 1: Overview and the central role for catecholamines and sympathetic nervous system

This is the first part of a scientific statement from the Heart Failure Association of the European Society of Cardiology focused upon the pathophysiology of Takotsubo syndrome and is complimentary to the previous HFA Position Statement on Takotsubo syndrome which focused upon clinical management. In part 1 we provide an overview of the pathophysiology of Takotsubo syndrome and fundamental questions to consider. We then review and discuss the central role of catecholamines and the sympathetic nervous system in the pathophysiology, and the direct effects of high surges in catecholamines upon myocardial biology including β-adrenergic receptor signaling, G protein coupled receptor kinases, cardiomyocyte calcium physiology, myofilament physiology, cardiomyocyte gene expression, myocardial electrophysiology and arrhythmogenicity, myocardial inflammation, metabolism and energetics. The integrated effects upon ventricular haemodynamics are discussed and integrated into the pathophysiological model. This article is protected by copyright. All rights reserved.

Toll-like receptor expression and apoptosis morphological patterns in female rat hearts with takotsubo syndrome induced by isoprenaline

AIMS

Toll-like receptors (TLR) and apoptosis were indicated as important factors in heart failure. Our aim was to characterize the morphological pattern of apoptosis, TLR2, TLR4, and TLR6 expression in female rat hearts in the model of takotsubo syndrome (TTS).

MAIN METHODS

60 Sprague-Dawley female rats were treated with a single dose of 150 mg/kg b.wt. of isoprenaline (ISO) or 0.9% NaCl (controls). Hearts were collected 24, 48, 72 h and 7 days post-ISO injection. 32/60 hearts were used in immunohistopathological studies and 28/60 in real time.

KEY FINDINGS

Apoptosis was observed 24 h post-ISO in cardiomyocytes, 24, 48, 72 h and 7 days post-ISO in infiltrating inflammatory cells, 7 days post-ISO in endothelial cells of vessels. Diffuse TLR4CD68 (CD68, a macrophage marker) and TLR6CD68 positive cells and TLR2, TLR4, TLR6 mononuclear cells were observed in both acute and recovery phase of TTS. In the foci located in the neighborhood of damaged (necrotic/apoptotic) cardiomyocytes in TTS, high (strong) protein expression of TLR2 (TLR2^high) was observed: 24, 48, 72 h post-ISO; TLR4^high - 48 and 72 h post-ISO; TLR6^high - 48 h post-ISO. Whereas in cardiomyocytes of remote myocardium: TLR2^high - 72 h post-ISO; TLR4^high - 24 and 72 h post-ISO; TLR6^high - 24 h post-ISO. TLR2 mRNA was down-regulated 48 and 72 h post-ISO whereas TLR4 up-regulated 7 days post-ISO.

SIGNIFICANCE

The expression pattern of apoptosis and TLR differs in the course of TTS in comparison with the control rats. We hypothesize that innate immunity and apoptosis may play a crucial role in TTS pathophysiology.

Low MMP-8/TIMP-1 reflects left ventricle impairment in takotsubo cardiomyopathy and high TIMP-1 may help to differentiate it from acute coronary syndrome

BACKGROUND

Matrix metalloproteinase 8 (MMP-8) is the most potent type-I collagen protease. Such collagen mainly constitutes the transient fibrosis in takotsubo cardiomyopathy (TTC) endomyocardial biopsies. High MMP-8 and tissue-inhibitor of matrix metalloproteinase-1 (TIMP-1) levels are implicated in acute coronary syndrome (ACS). We compared MMP-8 and TIMP-1 levels in consecutive TTC and ACS patients, and their association to TTC severity.

METHODS AND RESULTS

In 45 acute serum samples of TTC, 2072 ACS and 1000 controls, TIMP-1 differed between ACS 146.7ng/mL (115.0-186.3) (median (interquartile range)), TTC 115.7 (94.3-137.7) and controls 80.9 (73.2-90.4), (p<0.0001). MMP-8 levels were similar between ACS and TTC. In receiver-operating characteristics analysis, TIMP-1 differentiated TTC from ACS with an area under the curve (AUC) of 0.679 (p<0.0001) surpassing troponin T (TnT) at 0.522 (p = 0.66). Compared to other differing factors (age, sex, smoking), TIMP-1 improved diagnostic specificity and sensitivity from AUC of 0.821 to 0.844 (p = 0.007). The MMP8/TIMP-1 molar ratio differentiated normal ejection fraction (EF) at 0.27 (0.13-0.51) from decreased EF<50% at 0.08 (0.05-0.20), (p = 0.04) in TTC, but not in ACS.

CONCLUSIONS

Even with other differing factors considered, TIMP-1 differentiated TTC from ACS better than TnT. In TTC, the low MMP-8/TIMP-1 molar ratio may reflect decreased proteolysis and increased transient fibrosis, perhaps in part explaining the left-ventricle impairment.

Takotsubo cardiomyopathy: A potentially serious trap (Data from the International Takotsubo Cardiomyopathy Registry)

Takotsubo cardiomyopathy (TTC) is an acute cardiac condition characterized by transient left ventricular dysfunction with wall motion abnormalities, most commonly in the form of apical ballooning. Despite being considered as a generally benign condition, many studies have emphasized potentially sinister outcomes associated with TTC. In this article, we review the most recent results of the International Takotsubo Registry, which investigated the clinical features, prognostic predictors, and outcomes of 1750 patients.

Coronary flow reserve during dobutamine stress in Takotsubo stress cardiomyopathy

OBJECTIVES

Takotsubo stress cardiomyopathy (TSC) is an increasingly recognised and diagnosed disease, although the underlying pathophysiology is still unknown. Our aim was to investigate the effect of the catecholamine dobutamine on coronary flow reserve (CFR) measured non-invasively in patients with TSC and controls. Our hypothesis was that dobutamine stress can induce microvascular dysfunction in patients with a previous episode of TSC.

SETTING

This is a case-control study and a substudy of the Stockholm Myocardial Infarction with Normal Coronaries (SMINC) study. Elective dobutamine investigations were performed focusing on non-invasive measurements of CFR. The investigations were performed more than 6 months after the acute event.

PARTICIPANTS

22 patients with a previous episode of TSC and 22 sex-matched and age-matched controls were recruited from the SMINC study. All patients with TSC had a previous normal cardiovascular MR investigation.

RESULTS

CFR at low-dose dobutamine was significantly lower in the TSC group compared with controls, 1.51 and 1.72, respectively (p=0.017). At high-dose dobutamine, CFR was 1.95 and 2.21 in the TSC group and controls, respectively (p=0.098).

CONCLUSIONS

We could not confirm that the catecholamine dobutamine induced microvascular dysfunction in patients with TSC. However, we found a small but significant difference in CFR at low-dose dobutamine, which implies that the role of microvascular function in TSC needs to be further explored.

Epidemiology and pathophysiology of Takotsubo syndrome

Takotsubo syndrome is an acute cardiac syndrome first described in 1990 and characterized by transient left ventricular dysfunction affecting more than one coronary artery territory, often in a circumferential apical, mid-ventricular, or basal distribution. Several pathophysiological explanations have been proposed for this syndrome and its intriguing appearance, and awareness is growing that these explanations might not be mutually exclusive. The reversible apical myocardial dysfunction observed might result from more than one pathophysiological phenomenon. The pathophysiology of Takotsubo syndrome is complex and integrates neuroendocrine physiology, potentially involving the cognitive centres of the brain, and including the hypothalamic-pituitary-adrenal axis. Cardiovascular responses are caused by the sudden sympathetic activation and surge in concentrations of circulating catecholamines. The multiple morphological changes seen in the myocardium match those seen after catecholamine-induced cardiotoxicity. The acute prognosis and recurrence rate are now known to be worse than initially thought, and much still needs to be learned about the epidemiology and the underlying pathophysiology of this fascinating condition in order to improve diagnostic and treatment pathways.